Rubber products, including tires, are typically prepared of components of elastomer-based rubber compositions which are reinforced with a particulate carbon black. Sometimes such tire component rubber compositions also contain particulate silica reinforcement.
While carbon black is hydrophobic in nature and has a degree of compatibility with diene-based elastomers, silica (ie: particulate precipitated silica) is hydrophilic, or water absorbing, in nature and is not considered to be as readily compatible with diene-based elastomers
Further, compatibility of carbon black to diene-based elastomers is understood to be assisted by typically inherent Van der Waals attractive forces between the carbon black and diene-based elastomer(s) and contributes to the carbon black/elastomer compatibility.
Contrarily, it is understood that there is typically a minimal, if any, interaction of Van der Waals forces between precipitated silica and diene-based elastomer to aid in silica/elastomer compatibility.
In the description of this invention, the term "phr" where used herein, and according to conventional practice, refers to "parts of a respective material per 100 parts by weight of rubber, or elastomer". Usually the terms and percentages used herein are by weight unless otherwise indicated.
In the description of this invention, the terms "rubber" and "elastomer" if used herein, may be used interchangeably, unless otherwise prescribed. The terms "rubber compounded rubber" and "rubber compound", if used herein, are used interchangeably to refer to "rubber which has been blended or mixed with various ingredients and materials" and such terms are well known to those having skill in the rubber mixing or rubber compounding art.